Circumferentially expansible piston ring

ABSTRACT

A one-piece channel-type circumferentially expansible oilcontrol ring for pistons having a spring and reinforcing strut structure isolated from the portions of the ring which contact the piston and the cylinder. The ring has axially separated top and bottom rows of circumferentially separated radially extending segments or crowns held in axially spaced relation and having the crowns or segments of one row connected to circumferentially offset crowns in the other row by inclined legs on the inner periphery and also by reinforcing struts projecting between the rows. The crown, legs, and struts are so related as to minimize loss of metal strip stock from which the rings are formed and so as to eliminate the necessity for reducing the length of the stock to form the rings. The formation of the rings from the strip stock does not require length reducing folding so that the circumferential length of the finished ring is the same as the axial length of the original strip stock from which the ring was formed.

United States Patent [72] lnventor Arthur M. Brenneke New Castle, Ind. [211 AppLNo. 49,728 [22] Filed June25, 1970 [4S] Patented Nov.23,l97l I73] Aulgnee TRWlnc.

(Ileveland, Ohlo [54] C IRCUMFERENTIALLY EXPANSIBLE PISTON RING 7 Claims, 6 Drawlng Figs.

52 u.s.c| 277/138 [51] lnt.Cl Fl6j9/20 [50] FleldotSearch ..277/139-146 [56] References Cited UNITED STATES PATENTS 2,837,386 6/1958 Mayfield 277/139 3,136,559 6/1964 Hamm... 277/139 3,253,836 5/1966 Mamm 277/138 3,300,224 1/1967 Games Primary Examiner-Robert l. Smith A!!0rneyHill, Sherman, Meroni, Gross & Simpson which contact the piston and the cylinder. The ring has axially separated top and bottom rows of circumferentially separated radially extending segments or crowns held in axially spaced relation and having the crowns or segments of one row connected to circumferentially offset crowns in the other row by inclined legs on the inner periphery and also by reinforcing struts projecting between the rows. The crown, legs, and struts are so related as to minimize loss of metal strip stock from which the rings are formed and so as to eliminate the necessity for reducing the length of the stock to form the rings. The formation of the rings from the strip stock does not require length reducing folding so that the circumferential length of the finished ring is the same as the axial length of the original strip stock from which the ring was formed.

CIRCUMFERENTIALLY EXPANSIBLE PISTON RING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to the art of circumferentially expansible one-piece packing or sealing rings, and more particularly, deals with channel-type oil-control piston rings having axially spaced rows of circumferentially separated crowns or segments integrally connected through a spring and strut system.

2. Description of the Prior Art Channel-type circumferentially expansible oil-control rings with reinforcing struts in the channel are known, for example, in the prior art in the Engelhardt U.S. Pat. No. 2,345,589 dated Apr. 4, 1944. Such rings, however, have required wastage of metal strip stock from which the rings are formed both by way of cutout portions and foreshortening of the strip, and could only have one segment formed on each punch stroke.

SUMMARY OF THE INVENTION According to this invention wastage of ring stock is minimized, the necessity for foreshortening the axial length of the ring stock is eliminated, and channel-type circumferentially expansible piston rings are provided with leg and strut springs which do not engage either the cylinder or the ring groove so that they may flex freely within the confines of the ring. The ring is free from reverse bends or folds and the crowns or groove wall engaging segments of the ring have maximum radial depth and provide maximum cylinder wall engaging peripheral edges for the amount of strip stock that is used to produce the ring.

The preferred ring of this invention has a top row of circumferentially separated radially extending crowns or segments and an axially spaced bottom row of identical segments in staggered or offset relation to the top segments. Each top segment is connected to an adjacent bottom segment by an upstanding inclined leg. A strut extends from each side of each leg into the channel between the crowns with the strut on one side of the leg axially supporting one pair of crowns, and the strut on the opposite side of the leg supporting the next adjacent pair of crowns so that each crown is supported by two struts against axial collapse. The struts have central recesses dividing them into top and bottom spring fingers and upstanding strut portions connecting the spring fingers. The strut on one side of a leg is integral with one end of the leg and with the crown adjacent the other end of the leg.

One end of each crown is "L"-shaped, while the mating end of the adjacent crown is notched to receive the head of the L. This arrangement provides a radial gap between the segments with an offset outer peripheral portion.

A feature of the invention includes the maintenance of a reduced thickness connecting portion between the bottom of the notch and the end of the head of the L" for continuing the continuity of the strip stock during manufacture of the ring and for accommodating easy fracture to separate the segments at a desired step in the manufacturing process.

Another feature of the invention is the use of the struts at the ends of the ring to form abutment surfaces which will not permit the ends to overlap and will also accommodate uniting of the ends to form a continuous ring if desired.

It is then an object of this invention to provide a one-piece channel-type circumferentially expansible oil-control piston ring with a spring and strut system free from sharp reverse bends and from portions contacting either the piston groove or the cylinder.

Another object of this invention is to provide a one-piece circumferentially expansible channel-type oil-control ring for pistons which is formed from a minimum of metal strip stock and retains substantially all of the stock.

Another object of this invention is to provide a circumferentially expansible metal packing ring having axially spaced rows of circumferentially separated radially extending crowns connected in staggered relation by inclined inner peripheral legs from both sides of which struts extend between the rows of segments to reinforce them against axial collapse.

Another object of the invention is to provide an outwardly opening channel-type circumferentially expansible oil-control piston ring with two rings of axially spaced circumferentially separated segments and a pair of struts in the channel supporting each segment against axial collapse.

Another object of the invention is to provide a split channeltype circumferentially expansible oil-control ring for pistons with radial struts at the ends of the ring in the channel providing abutment surfaces preventing overlapping of the ring ends in a piston ring groove.

Other and further objects of this invention will become apparent to those skilled in this art from the following detailed description of the annexed sheet of drawings which, by way of a preferred example only, illustrates one embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a piston ring according to this invention;

FIG. 2 is an enlarged transverse section of the ring of FIG. I mounted in a piston and cylinder assembly;

FIG. 3 is a fragmentary isometric view of the ring of FIG. I with portions broken away to show underlying parts;

FIG. 4 is a fragmentary front side elevational view of the ring ofFIG. 1;

FIG. 5 is a plan view of a portion of a punched strip of piston ring metal providing the blank for forming the ring of FIG. I;

FIG. 6 is a view similar to FIG. 5 but showing the blank in folded channel form.

DESCRIPTION OF THE PREFERRED EMBODIMENT The ring I0 of FIG. 1 is split at 11 and is composed of a top ring of circumferentially separated segments I2 and a bottom ring of similar segments 13. Legs 14 at spaced intervals around the inner periphery of the ring connect the segments in one ring with adjacent segments in the other ring and hold the segments in axially spaced relation, thus providing an outwardly opening channel 15 between the rings of segments. Reinforcing struts 16 extend from opposite sides of the legs I4 into the channel I5 to form supporting columns for preventing axial 'collapse of the top and bottom rings of segments I2 and I3.

The segments 12 and 13 are cut at the split ends II of the ring so that the struts I6 will form radial end walls for the ring and will be abutted together when the ring is contracted in operation in a piston and cylinder assembly as shown in FIG. 2.

In FIG. 2, the ring 10 is seated in the oil ring groove I7 of a piston P mounted in a cylinder C of an internal combustion engine. The ring groove 17 is connected by holes or slots I8 to the interior of the piston as is customary in oil ring rooves. The ring I0 in the groove 17 has the top segments I2 riding on the top sidewall of the groove with the bottom segments I3 riding on the bottom sidewall of the groove. The peripheral edges of the segments 12 provide a top scraping edge 19 riding on the cylinder wall, while the peripheral edges of the segments I3 provide a bottom scraping edge 20 riding on this wall. A strut 16 is illustrated as abutting the inner faces of the segments 12 and 13 to hold them in flat radial parallel position. A leg I4 on the inner periphery of the ring 10 is illustrated as connecting the top and bottom segments 12 and 13. It will be noted that in operation, when the ring I0 is contracted in the groove 17 the inner periphery of the ring is spaced radially outward from the bottom of the groove.

As best shown in FIG. 3, the segments I2 are separated by radially extending slots 21 extending from the inner periphery of the ring to a circumferential slot 22 near the outer periphery of the ring having its outer end connected to the outer periphery of the ring by a radial slot 23. Thus, one end of each segment I2 is L"-shaped and the mating end of the adjoining segment is notched to receive the base of the The bottom segments 13 are similarly separated by radial slots 24 extending from the inner periphery of the ring to circumferential slots 25 which terminate in radial slots 26 to the outer periphery of the ring, but it will be noted that the L- shaped ends and notched ends are reversed so that the outer slots 23 in the top ring of segments 12 are circumferentially offset from the slots 26 in the bottom ring of segments 13. The provision of shaped ends and notched ends on the segments and the offsetting of these ends in the top and bottom segments is desirable to provide a better seal between the segments when the ring is contracted in use.

As also shown in FIG. 3, the legs of 14 are inclined circumferentially to extend from the inner end portion of a segment 13 to the inner end of the next adjacent top segment 12, thus fonning an upstanding base leg connecting the segments together with the segments in one ring being connected through the segments in the other ring.

As further shown in H0. 3, the struts 16 are positioned in pairs on each side of the legs 14. One strut 16 of each pair is connected to the bottom end of the leg 14 and to the inner peripheral portion of the top segment 12, while the other strut 16 of each pair is connected to the opposite top end of the leg 14 and to the inner peripheral edge of the bottom segment 13.

As shown in FIG. 4, the slots 23 lie on one side of the leg 14, while the slots 26 lie on the opposite side of the leg and the struts 16 of each pair straddle the slots 23 and 26. These struts do not extend to the outer peripheral edges 19 being terminated radially inward as shown in FIG. 3.

A further understanding of the ring structure will become apparent from the blanks shown in FIGS. and 6 from which the ring is formed.

As shown in FIG. 5, a strip of piston ring metal stock 27 is punched to provide a first row of axially spaced longitudinally elongated holes 28 and a second similar row of holes 29 in spaced parallel relation with the first row. Between the rows of holes 28 and 29, a central row of holes 30 is punched. These holes are paired with rounded outer ends 30a and diagonal inner ends 3012. The strip 27 is sliced diagonally 31 and 32 registering with the sloping ends 30b of the punched out portions 30. The cut 31 merges with a transverse cut 33 on one side of the strip, while the cut 32 merges with an aligned cut 34 on the opposite side of the strip. The cut 33 registers with a longitudinal cut 35 extending toward the left-hand end of the strip which terminates in a transverse cut 36 to the side edge of the strip. The cut 34 merges with a longitudinal cut 37 extending toward the right-hand end of the strip, and this cut terminates in a transverse cut 38 to the opposite edge of the strip. These cuts separate the above described segments 12 and 13 and the legs 14.

The strip 27 also has transverse central cuts 39 and parallel longitudinal cuts 40 extending from the ends of the cuts 39 into the punched holes 28 and 29 respectively. These cuts isolate the struts l6 and it will thus be noted that the struts l6 lie on opposite sides of the legs 14 with the struts 16 on the left side of the legs being connected to the lower side ends of the legs and with the struts on the right side of the legs being connected to the upper side ends of the legs.

The blank 27 is folded from the flat state of FIG. 5 to channel form of FIG. 6 by bending the strip along the fold lines A and B illustrated in FIG. 5. The struts are then bent into the channel by bending along the fold lines C and D of FIG. 5.

if desired, the cuts 36 and 38 may not be cut completely through the strip 27 so as to leave weakened reduced thickness portions which are easily fractured after the blank is folded, coiled and hardened.

The punched out portions 30 of the blank divide the struts 16 into top and bottom finger portions 16a connected by an upstanding leg portion 16b. The punched out holes 28 and 29 surfaces preventingoverlapping of the ends in the ring groove. The ring has a spring system independent of the contacting surfaces of the ring with either the ring groove or the cylinder wall and utilizes substantially all of the strip stock from which it is formed without foreshortening the strip stock. The abutted end struts of the ring can be welded or otherwise secured, if it is desired, to provide a continuous ring.

l claim as my invention:

1. A one-piece channel-type circumferentially expansible oil-control ring for pistons which comprises a metal strip folded into an outwardly opening channel ring with axially spaced peripheral scraping edges, said ring having circumferentially separated top and bottom crowns connected by inclined spring legs at spaced intervals around the inner periphery of the ring, struts on each side of each leg folded into the channel supporting the crowns, said ring being split and having struts at the split ends thereof forming abutting surfaces to prevent overlap of the ends of the ring.

2. The piston ring of claim 1 wherein each strut has top and bottom finger portions connected by an upstanding leg portion engaging the top and bottom crowns.

3. The piston ring of claim 1 wherein each leg portion has a bottom end connected to the bottom end of one strut and the top end of this strut is connected to the next adjacent top crown.

4. An oil-control piston ring of the circumferentially expansible type having a spring system free from portions which will engage the ring groove or the cylinder wall during use of the ring in a piston and cylinder assembly which comprises a sheet metal split ring defining an outwardly opening channel, said ring having a top row of circumferentially separated radially extending crowns'in axially spaced parallel relation with the first row, upstanding spring legs at spaced intervals around the inner periphery of the ring, each leg having the bottom end thereof connected to a bottom crown at the circumferential extremity thereof and the top end thereof connected to the next adjacent top crown at the circumferential extremity thereof, and struts on both sides of each leg extending therefrom into the channei and engaging the top and bottom crowns to support the same against axial collapse.

5. The piston ring of claim 4 wherein each leg has a pair of crowns folded radially outward therefrom into the channel between the top and bottom crowns.

6. The piston ring of claim 4 formed from a continuous strip of metal from which only small holes are punched.

7. A one-piece split circumferentially expansible channeltype oil ring for pistons which comprises a top ring of circumferentially separated radially extending crowns, a bottom ring of circumferentially separated radially extending crowns, the crowns in the top and bottom rows having mated L"-shaped and notched circumferential ends with the L-shaped ends on the top row of crowns being opposite the L"-shaped ends on the bottom row of crowns to stagger the gaps between the crowns in the top and bottom rows, said top and bottom crowns being connected by upstanding inclined legs on the inner periphery of the ring with each leg connecting a bottom crown with the next adjacent circumferentially offset top crown, and strut means extending from the legs between the top and bottom crowns to hold the crowns against axial collapse.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,622,166 Dated November 23, 1971 ARTHUR M. BR ENNEKE Patent No.

Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 38 (line 7 of claim 4), after "crowns" insert "and a bottom row of circumferentially separated radially extending crowns".

Signed and sealed this 6th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DC 603754 69 ORM PO-105O (10-69) 0 us sovzmmem' Pmm'mo OFFICE 1909 O366-J3l 

1. A one-piece channel-type circumferentially expansible oilcontrol ring for pistons which comprises a metal strip folded into an outwardly opening channel ring with axially spaced peripheral scraping edges, said ring having circumferentially separated top and bottom crowns connected by inclined spring legs at spaced intervals around the inner periphery of the ring, struts on each side of each leg folded into the channel supporting the crowns, said ring being split and having struts at the split ends thereof forming abutting surfaces to prevent overlap of the ends of the ring.
 2. The piston ring of claim 1 wherein each strut has top and bottom finger portions connected by an upstanding leg portion engaging the top and bottom crowns.
 3. The piston ring of claim 1 wherein each leg portion has a bottom end connected to the bottom end of one strut and the top end of this strut is connected to the next adjacent top crown.
 4. An oil-control piston ring of the circumferentially expansible type having a spring system free from portions which will engage the ring groove or the cylinder wall during use of the ring in a piston and cylinder assembly which comprises a sheet metal split ring defining an outwardly opening channel, said ring having a top row of circumferentially separated radially extending crowns in axially spaced parallel relation with the first row, upstanding spring legs at spaced intervals around the inner periphery of the ring, each leg having the bottom end thereof connected to a bottom crown at the circumferential extremity thereof and the top end thereof connected to the next adjacent top crown at the circumferential extremity thereof, and struts on both sides oF each leg extending therefrom into the channel and engaging the top and bottom crowns to support the same against axial collapse.
 5. The piston ring of claim 4 wherein each leg has a pair of crowns folded radially outward therefrom into the channel between the top and bottom crowns.
 6. The piston ring of claim 4 formed from a continuous strip of metal from which only small holes are punched.
 7. A one-piece split circumferentially expansible channel-type oil ring for pistons which comprises a top ring of circumferentially separated radially extending crowns, a bottom ring of circumferentially separated radially extending crowns, the crowns in the top and bottom rows having mated ''''L''''-shaped and notched circumferential ends with the ''''L''''-shaped ends on the top row of crowns being opposite the ''''L'''' -shaped ends on the bottom row of crowns to stagger the gaps between the crowns in the top and bottom rows, said top and bottom crowns being connected by upstanding inclined legs on the inner periphery of the ring with each leg connecting a bottom crown with the next adjacent circumferentially offset top crown, and strut means extending from the legs between the top and bottom crowns to hold the crowns against axial collapse. 